Estimation of porcine pancreas optical properties in the 600–1100 nm wavelength range for light-based therapies

Abstract

Abstract This work reports the optical properties of porcine pancreatic tissue in the broad wavelength range of 600–1100 nm. Absorption and reduced scattering coefficients (µ a and µ s′) of the ex vivo pancreas were obtained by means of Time-domain Diffuse Optical Spectroscopy. We have investigated different experimental conditions—including compression, repositioning, spatial sampling, temporal stability—the effect of the freezing procedure (fresh vs frozen-thawed pancreas), and finally inter-sample variability. Good repeatability under different experimental conditions was obtained (median coefficient of variation less than 8% and ~ 16% for µ a and µ s′, respectively). Freezing–thawing the samples caused an irreversible threefold reduction of µ s′ and no effect on µ a. The absorption and reduced scattering spectra averaged over different samples were in the range of 0.12–0.74 cm−1 and 12–21 cm−1 with an inter-sample variation of ~ 10% and ~ 40% for µ a and µ s′, respectively. The calculated effective transport coefficient (µ eff ) for fresh pancreatic tissue shows that regions between 800–900 nm and 1050–1100 nm are similar and offer the lowest tissue attenuation in the considered range (i.e., µ eff ranging from 2.4 to 2.7 cm−1). These data, describing specific light-pancreas interactions in the therapeutic optical window for the first time, provide pivotal information for planning of light-based thermotherapies (e.g., laser ablation) and instruction of light transport models for biophotonic applications involving this organ.